I typically use xScope for all of my on-screen pixel measuring needs, but recently, I’ve often found myseful using SnapRuler instead. It’s very simple, but has three really useful features.

First, hitting shift immediately snaps the measuring rectangle to the nearest visible edge (like the border of a button or window). Second, once you’ve measured something, you can copy the values as CSS or Objective-C code, and directly paste them into your text file. And third, you can easily resize your selection rectangle by single pixels using the arrow keys (something I have to do often when I’m working with a trackpad).

Both xScope and SnapRuler are really nifty, and get along nicely with each other.

Want to read more like this? Buy my book's second edition! Designed for Use: Create Usable Interfaces for Applications and the Web is now available DRM-free directly from The Pragmatic Programmers. Or you can get it on Amazon, where it's also available in Chinese and Japanese.

Hi. My name is Lukas Mathis. I studied Computer Science/Software Engineering and Ergonomics/Usability at ETH Zürich. I work as a software engineer and user interface designer for a swiss software company creating process management software. I've written a book about usability. It's been translated to Chinese and Japanese. My first computer was a Performa 450, my first programming language was HyperTalk, my first electric guitar was a cheap Peavey, my first videogame was a VCS 2600 and my current snowboard is from Lib Tech. I live in a small cottage in a remote part of the Swiss Alps, and you can reach me at or on twitter.